Barrier devices and personal protection systems are used in medical and surgical procedures to provide a sterile barrier between the surgical personnel and the patient. During such procedures (and especially during orthopedic operations), a drill or powered saw often generates spray, splash, and aerosol from a patient's surgical wound to the surgeon. This exposes the surgeon to a risk of infection. Traditional surgical masks and cups are not capable of completely keeping the sterility of the surgical wound. In some cases, bodily materials from a surgical team (e.g., sweat, hair, dandruff, or even saliva) may infect the patient. For these reasons, especially in orthopedic surgery, a surgical helmet has been used for many years. A conventional surgical helmet may include a battery-powered fan for air circulation and a sterile hood that covers the helmet and has a transparent visor, lens, or other vision element.
One such system is disclosed in U.S. Pat. No. 5,054,480, the contents of which are incorporated herein by reference discloses that basic structure of such a system. Specifically, the traditional system includes a helmet that supports a toga, also known as a drape or hood. (The terms “toga”, “drape”, and “hood” are used interchangeably herein and are intended to have the same meaning.) This assemblage is worn by medical personnel who want to establish the sterile barrier. The hood includes a transparent face shield. The helmet includes a ventilation unit that includes a fan. The ventilation unit draws air through the hood so the air is circulated around the wearer. This reduces both the amount of heat that is trapped within the toga/hood and the carbon dioxide (CO2) that builds up in this space. It is further known to mount a light to the helmet. The light, which is directed through face shield illuminates the surgical site.
Donning a hood creates a closed chamber around the operator's head, which represents both a heating element (by means of radiation and/or convection) and a source of hot and humid respiratory air with significant CO2 concentrations up to 40,000 ppm. Without air exchange between the chamber and the ambient environment, a so called “sauna effect” is created, leading to temperatures of up to 32° C., humidity levels of up to 85% (relative humidity) and CO2 concentrations of up to 40,000 ppm inside the chamber. To avoid this effect, state of the art surgical protection systems include hoods with a filter element, which supports air exchange and provides breathability as well. This is typically accomplished using fans that move air into the chamber and circulate air within the chamber.
Other personal protection systems are disclosed in U.S. Pat. No. 6,481,019 to Diaz et al., in U.S. Pat. No. 9,173,437 to VanDerWoude et al., and in U.S. patent application Ser. No. 13/984,908 filed by Giorgio Rosati et al., the contents of each of which is incorporated by reference in its entirety. VanDerWoude et al., for example, describes a system having a hood, a fan, a light, and a helmet with control switches that a user actuates by hand.